Question 1

Table 40.1 -What role does Na⁺/K⁺- ATPase play in salt excretion by the shark rectal gland?

Accepted Answer

Na+/K+-ATPase pumps sodium out of cells and potassium into cells across the basolateral membrane, which is crucial for maintaining the electrochemical gradients that drive various physiological processes, including salt excretion in the shark rectal gland.

Question 2

The body fluids of an osmoconformer would be with its environment.

Accepted Answer

Osmoconformers are organisms that maintain their internal fluids isotonic with their surrounding environment. In the case of saltwater environments, this means their body fluids are isoosmotic with the saltwater around them, allowing them to minimize the energy expended on osmoregulation.

Question 3

Marine vertebrates live in an) environment.

Accepted Answer

C

Question 4

Salmon eggs hatch in freshwater. The fish then migrate to the ocean a hypertonic solution) and, after several years of feeding and growing, return to freshwater to breed. How can these organisms make the transition from freshwater to ocean water and back to freshwater?

Accepted Answer

Different gill cells are involved in osmoregulation in freshwater than in salt water, allowing salmon to adapt to the varying salinity levels of their environments.

Question 5

A necropsy postmortem analysis) of a marine sea star that died after it was mistakenly placed in freshwater would likely show that it died because

Accepted Answer

Marine organisms have adapted to a hypertonic environment, so when they are placed in freshwater, they cannot osmoregulate and end up taking in too much water which causes cellular damage and ultimately death. The other options are not likely to be the cause of death in this scenario.

Question 6

Terrestrial organisms lose water through evaporation. Why are desert locusts and flour beetles good organisms to use in studying mechanisms to regulate water loss?

Accepted Answer

Desert locusts and flour beetles are excellent organisms to study mechanisms to regulate water loss because they live in environments where water is scarce, so they have developed adaptations to conserve water. These adaptations include reducing water loss through their cuticles and respiratory surfaces, and adjusting their behavior to avoid water loss during the hottest parts of the day.

Question 7

Which of the following affects the osmolarity of a solution?

Accepted Answer

Osmolarity refers to the concentration of solutes in a solution, so any solute concentration (such as salt or glucose) will affect the osmolarity. Water concentration is also important because it determines the volume of the solution, which can affect the concentration of solutes. Therefore, all three choices (water, salt, and glucose concentration) affect the osmolarity of a solution.

Question 8

Which of the following mechanisms contributes to osmoregulation in both marine and freshwater bony fish?

Accepted Answer

The answer of Which of the following mechanisms contributes to...

Question 9

Tissues of sharks are isotonic to seawater, but their concentrations of sodium ions, potassium ions, and chloride ions in cells and extracellular fluids are similar to those of freshwater fishes. What can you infer about the movement of sodium and chloride in these animals?

Accepted Answer

The answer of Tissues of sharks are isotonic to seawater,...

Question 10

Sharks live in seawater. Their tissues are isotonic to seawater, but their concentrations of sodium ions, potassium ions, and chloride ions in cells and extracellular fluids are similar to those of freshwater fishes. How is that possible?

Accepted Answer

Sharks have other compounds contributing to intra- and extracellular osmolarity in their tissues, such as urea and trimethylamine oxide. These compounds help them maintain a balance of ions in their cells and extracellular fluids despite living in seawater.

Question 11

Which of the following are soluble compounds that contribute to intracellular osmolarity in shark tissues?

Accepted Answer

Urea and trimethylamine oxide are soluble compounds that are found in high concentrations in the tissues of sharks to help maintain their internal osmotic balance. Glucose and amino acids may also contribute, but to a lesser extent. Excessively high levels of sodium and chloride would actually contribute to an increase in extracellular osmolarity and the need for the shark to regulate its internal balance. A proton pump is not a soluble compound and would not contribute to intracellular osmolarity.

Question 12

African lungfish, which are often found in small, stagnant pools of freshwater, produce urea as a nitrogenous waste. What is the advantage of this adaptation?

Accepted Answer

Small, stagnant pools do not provide enough water to dilute the toxic ammonia produced by other aquatic animals. Urea is less toxic than ammonia and requires less water to be excreted, making it a better waste product for animals living in such conditions.

Question 13

What is the function of the shark rectal gland?

Accepted Answer

The shark rectal gland is an important component of their osmoregulatory system. Sharks live in a hypertonic environment, meaning that the concentration of salts in the water is higher than in their bodies. To maintain proper electrolyte balance, they must excrete excess salts. The rectal gland is responsible for producing a concentrated salt solution that is expelled from the body as urine, helping to regulate electrolyte levels. Therefore, option B is the correct choice.

Question 14

Which of the following is an example of osmoregulation?

Accepted Answer

Osmoregulation refers to the control of water balance and solute concentrations in living organisms. The contractile vacuole of a Paramecium is an example of osmoregulation as it helps the organism maintain its water balance by pumping out excess water. Option B refers to a state where there is no osmotic pressure difference between two solutions and is not an example of osmoregulation. Option C refers to a medical condition and is not relevant to osmoregulation.

Question 15

Table 40.1
-The intercellular concentration of three electrolytes is compared with the concentration of these electrolytes in fluid eliminated from the shark rectal gland in Table 40.1. Based on the data, which of the following is a likely function of the rectal gland?

Accepted Answer

The data in Table 40.1 shows that the concentration of Na+, K+, and Cl- in the fluid eliminated from the shark rectal gland is much higher than their intercellular concentrations, suggesting that the rectal gland is able to actively concentrate these electrolytes. This function is particularly important for sharks, which live in a seawater environment where they constantly lose water and electrolytes osmotically. Option A, regarding the elimination of metabolic waste, is not supported by the data in the table. Option C, stating that there is very little potassium in sharks, is not supported by any evidence. Option D, regarding chloride levels in seawater and shark tissues, is not directly addressed by the data in the table.

Question 16

What role do chloride cells play in osmoregulation of marine fish with bony skeletons?

Accepted Answer

Chloride cells in marine fish gills are specialized for excreting excess salt, helping the fish maintain osmotic balance in a salty environment.

Question 17

The force driving simple diffusion is

Accepted Answer

Simple diffusion is driven by a concentration gradient, where molecules move from an area of higher concentration to an area of lower concentration without the use of transmembrane pumps or phosphorylated protein carriers, and without requiring ATP.

Question 18

Freshwater fish reside in hypotonic environments. They do not drink water, and they excrete large volumes of hypotonic urine in an effort to osmoregulate. How do they obtain an adequate supply of electrolytes?

Accepted Answer

Freshwater fish obtain electrolytes by absorbing them through their gill lamellae from the surrounding water.

Question 19

Freshwater fish live in a hypotonic environment. To maintain homeostasis in this environment, they must

Accepted Answer

Freshwater fish live in a hypotonic environment where water tends to enter their bodies. To maintain homeostasis, they excrete large quantities of water to prevent their cells from swelling and bursting.

Question 20

Table 40.1 -Refer to Table 40.1: Because the shark rectal gland functions only when ATP molecules are present, what can you infer about the movement of Na⁺, K⁺, and Cl^-?

Accepted Answer

The fact that the shark rectal gland only functions in the presence of ATP molecules indicates that the movement of Na+, K+, and Cl- ions into the gland is an active process rather than a passive one, which rules out choices B and C. Additionally, the ability of the gland to concentrate ions is implied by the fact that it requires ATP to function, so D can also be ruled out. Therefore, the best choice is A.

Quiz 40: Water and Electrolyte Balance in Animals

Table 40.1 -What role does Na+/K+- ATPase play in salt excretion by the shark rectal gland?